Re: [PATCH v2] drm/i915/bxt: use NULL for GPIO connection ID

[Jani Nikula <jani.nikula@intel.com>]

On Thu, 17 Aug 2017, Mika Kahola <mika.kahola@intel.com> wrote:
> Tested with GLK + MIPI/DSI panel (AU Optronics B101UAN01)
>
> Tested-by: Mika Kahola <mika.kahola@intel.com>

Do we have a bxt system available for testing this? With that,

Acked-by: Jani Nikula <jani.nikula@intel.com>

BR,
Jani.


>
> On Thu, 2017-08-17 at 13:55 +0300, Andy Shevchenko wrote:
>> The commit 213e08ad60ba
>> 	("drm/i915/bxt: add bxt dsi gpio element support")
>> enables GPIO support for Broxton based platforms.
>> 
>> While using that API we might get into troubles in the future,
>> because
>> we can't rely on label name in the driver since vendor firmware might
>> provide any GPIO pin there, e.g. "reset", and even mark it in _DSD
>> (in
>> which case the request will fail).
>> 
>> To avoid inconsistency and potential issues we have two options:
>> a) generate GPIO ACPI mapping table and supply it via
>>    acpi_dev_add_driver_gpios(), or
>> b) just pass NULL as connection ID.
>> 
>> The b) approach is much simpler and would work since the driver
>> relies
>> on GPIO indices only. Moreover, the _CRS fallback mechanism, when
>> requesting GPIO, has been made stricter, and supplying non-NULL
>> connection ID when neither _DSD, nor GPIO ACPI mapping is present, is
>> making request fail.
>> 
>> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=101921
>> Fixes: f10e4bf6632b ("gpio: acpi: Even more tighten up ACPI GPIO
>> lookups")
>> Cc: Mika Kahola <mika.kahola@intel.com>
>> Cc: Jani Nikula <jani.nikula@intel.com>
>> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
>> ---
>> v2:
>>  - adjust commit message for proper time tenses
>>  - add Fixes: and Bugzilla: tags
>>  drivers/gpu/drm/i915/intel_dsi_vbt.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>> 
>> diff --git a/drivers/gpu/drm/i915/intel_dsi_vbt.c
>> b/drivers/gpu/drm/i915/intel_dsi_vbt.c
>> index 7158c7ce9c09..91c07b0c8db9 100644
>> --- a/drivers/gpu/drm/i915/intel_dsi_vbt.c
>> +++ b/drivers/gpu/drm/i915/intel_dsi_vbt.c
>> @@ -306,7 +306,7 @@ static void bxt_exec_gpio(struct drm_i915_private
>> *dev_priv,
>>  
>>  	if (!gpio_desc) {
>>  		gpio_desc = devm_gpiod_get_index(dev_priv->drm.dev,
>> -						 "panel",
>> gpio_index,
>> +						 NULL, gpio_index,
>>  						 value ?
>> GPIOD_OUT_LOW :
>>  						 GPIOD_OUT_HIGH);
>>  

-- 
Jani Nikula, Intel Open Source Technology Center
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